linux-kernel - Re: [PATCH v5 1/5] Revert "KVM: X86: Fix setup the virt_spin_lock

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Message-ID: <87imot57x3.fsf@vitty.brq.redhat.com>
Date:   Sun, 13 Oct 2019 11:08:56 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Zhenzhong Duan <zhenzhong.duan@...cle.com>,
        linux-kernel@...r.kernel.org
Cc:     linux-hyperv@...r.kernel.org, kvm@...r.kernel.org,
        kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        sashal@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, pbonzini@...hat.com, rkrcmar@...hat.com,
        sean.j.christopherson@...el.com, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org, boris.ostrovsky@...cle.com,
        jgross@...e.com, sstabellini@...nel.org, peterz@...radead.org,
        Zhenzhong Duan <zhenzhong.duan@...cle.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v5 1/5] Revert "KVM: X86: Fix setup the virt_spin_lock_key before static key get initialized"

Zhenzhong Duan <zhenzhong.duan@...cle.com> writes:

> This reverts commit 34226b6b70980a8f81fff3c09a2c889f77edeeff.
>
> Commit 8990cac6e5ea ("x86/jump_label: Initialize static branching
> early") adds jump_label_init() call in setup_arch() to make static
> keys initialized early, so we could use the original simpler code
> again.
>
> The similar change for XEN is in commit 090d54bcbc54 ("Revert
> "x86/paravirt: Set up the virt_spin_lock_key after static keys get
> initialized"")
>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Radim Krcmar <rkrcmar@...hat.com>
> Cc: Sean Christopherson <sean.j.christopherson@...el.com>
> Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
> Cc: Wanpeng Li <wanpengli@...cent.com>
> Cc: Jim Mattson <jmattson@...gle.com>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> ---
>  arch/x86/kernel/kvm.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index e820568..3bc6a266 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -527,13 +527,6 @@ static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
>  	}
>  }
>  
> -static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
> -{
> -	native_smp_prepare_cpus(max_cpus);
> -	if (kvm_para_has_hint(KVM_HINTS_REALTIME))
> -		static_branch_disable(&virt_spin_lock_key);
> -}
> -
>  static void __init kvm_smp_prepare_boot_cpu(void)
>  {
>  	/*
> @@ -633,7 +626,6 @@ static void __init kvm_guest_init(void)
>  		apic_set_eoi_write(kvm_guest_apic_eoi_write);
>  
>  #ifdef CONFIG_SMP
> -	smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
>  	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
>  	if (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
>  	    !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
> @@ -835,8 +827,10 @@ void __init kvm_spinlock_init(void)
>  	if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
>  		return;
>  
> -	if (kvm_para_has_hint(KVM_HINTS_REALTIME))
> +	if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
> +		static_branch_disable(&virt_spin_lock_key);
>  		return;
> +	}
>  
>  	/* Don't use the pvqspinlock code if there is only 1 vCPU. */
>  	if (num_possible_cpus() == 1)

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

-- 
Vitaly